Reporting threshold defined

A ull-time employee," for purposes of section 313 reporting, is defined as 2,000 work hours per year. To determine the number of full-time employees atyourfacility, add up the hours worked by all employees during the calendar year, including contract employees and sales and support staff working at the facility and divide the total by 2,000 hours. In other words, if the total numter of hours worked by all employees is 20,000 hou rs or more, your facility meets the ten employee threshold. 

All of the hazard and benchmark criteria developed for the Green Screen are presented in the report, along with information on government and other precedents for classification that were used to help establish the thresholds. The hst of hazard categories and threshold values used to define levels of concern in the Green Screen are presented in Table 8.1. 

Filter samples can be prepared to airborne workplace concentrations by spiking each filter with aqueous solution containing elements with concentrations gravimetrically traceable to ultrapure metals or stoidiiometricaUy well defined oxides. The amormts correspond for some of the materials to current threshold limit values of contaminants in workroom atmospheres provided that the simulated filter has been exposed to one cubic meter of air. The certified values are based on a gravimetric procedure, i.e. weight per volume composition of the primary reference material dissolved in high purity sub-dis-tiUed acids. The National Institute of Occupational Health in Oslo, Norway, has produced several batches of such materials certified for 20 elements. Additionally, information values are reported for four other elements see Table 6.2. 

If the threshold and minimum peak heights/areas were appropriately defined, then only peaks 1 and 7-12 would be integrated, making the report much easier to read. 

Ozone and sulfur dioxide mixtures are of special interest, because of their widespread occurrence and the greater than additive effect on Bel W, tobacco. Concentrations of either or both that may cause foliar injury are found around major metropolitan areas throughout the world and are widespread throughout rural eastern United States. Macdowall and Cole reported that the two-gas combination lowered the threshold for injury of tobacco (cultivar White Gold) by sulfur dioxide, but not the threshold for ozone injury. Macdowall et defined the threshold in terms of dose when th reported the threshold at 20 pphm-h (0.20 ppm-h). This has not appeared true in several other reports, nor within the results reported by Macdowall and Cole. Symptoms reported, when sulfur dioxide was below the threshold for the specific plant, were similar to those reported for ozone. 

As a compromise between the above two approaches, the third approach adopts nonactive (inert) materials as working electrodes with neat electrolyte solutions and is the most widely used voltammetry technique for the characterization of electrolytes for batteries, capacitors, and fuel cells. Its advantage is the absence of the reversible redox processes and passivations that occur with active electrode materials, and therefore, a well-defined onset or threshold current can usually be determined. However, there is still a certain arbitrariness involved in this approach in the definition of onset of decomposition, and disparities often occur for a given electrolyte system when reported by different authors Therefore, caution should be taken when electrochemical stability data from different sources are compared. 

The confirmation rates for the selected set at different primary and confirmation percent inhibition thresholds appear in Table 6.2. Also shown are confirmation rates for those subsets of the selected that appear in the Top X selection either before or after filtering, which is the union of the selected set and the respective Top 4000 selections. The confirmation rate holds remarkably steady for all three sets at the four different thresholds for the primary inhibition examined if the threshold used to define confirmed actives is kept constant at 30%. If the confirmation threshold is instead increased along with the primary threshold, the confirmation rate drops for all three sets, which might be considered counterintuitive. However, this can be explained by the twin influences of edge effects (Section 6.1.5) and the enrichment of false positives at higher activities. This behavior has been reported previously by Fay and Ullmann [31] for both real... 

WHO/IPCS (1994, 1996, 1999) did not consider an extrapolation factor for duration of exposure specifically, but the uncertainty related to this element is included in a broader defined additional factor addressing the adequacy of the overall database (Section 5.9). The US-EPA (1993) has adopted the 10-fold factor to account for the uncertainty involved in extrapolating from less than chronic NOAELs to chronic NOAELs. This default value has later on been reconfirmed (US-EPA 2002) when only a subchronic duration smdy is available to develop a chronic reference value no chronic reference value is derived if neither a subchronic nor a chronic smdy is available. For systemic effects, ECETOC (2001) recommended a default assessment factor of 6 for extrapolation from subacute (28 days) to chronic exposure, and a factor of 2 from subchronic (90 days) to chronic exposure. For local effects, no additional assessment factor is needed for duration of exposure extrapolation for substances with a local effect below the threshold of cytotoxicity. KEMl (2003) suggested that extrapolation from subchronic to chronic exposure should be based on the distribution of NOAEL ratios reported by Vermeire et al. (2001) with an assessment factor of 16 covering 95% of the substances compared and for extrapolation from subacute to chronic exposure, with an assessment factor of 39 covering 95% of the substances. 

Exposure levels leading to effects on the central nervous systems of humans are not precisely defined. No symptoms of lightheadedness or nausea were experienced by humans exposed to 50 ppm for 70 minutes or 10 ppm for 3 hours (Stewart et al. 1961), but nausea, headache, and giddiness were found to be common symptoms in workers exposed to carbon tetrachloride for 8 hours a day at concentrations of 20-125 ppm (Elkins 1942 Heimann and Ford 1941 Kazantzis and Bomford 1960). Dizziness has also been reported in humans following short-term exposure (15 minutes) at a higher concentration (250 ppm) (Norwood et al. 1950). This suggests that the threshold for central nervous system effects in humans is probably in the range of 20-50 ppm for an 8-hour workday. 

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